1. Limited Copyright Waiver
A portion of the disclosure of this patent document contains computer code listings and command formats to which the claim of copyright protection is made. The copyright owner has no objection to the facsimile reproduction by any person of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but reserves all other rights whatsoever.
2. Field of the Invention
The present invention relates generally to data storage systems, and more particularly to data recovery in a data storage system using remote data replication.
3. Description of the Related Art
Remote copy systems have been used for automatically providing data backup at a remote site in order to insure continued data availability after a disaster at a primary site. Such a remote copy facility is described in Ofek, U.S. Pat. No. 5,901,327 issued May 4, 1999, entitled “Bundling of Write Data from Channel Commands in a Command Chain for Transmission over a Data Link Between Data Storage Systems For Remote Data Mirroring,” incorporated herein by reference. This remote copy facility uses a dedicated network link and a link-layer protocol for 1:1 replication between a primary storage system and a secondary storage system. This kind of remote copy system is relatively expensive, however, because a secondary storage system and a network link are dedicated for backup purposes.